The present version of South Island, which has apperently risen out of the water a bit with the power of the Chaos Emeralds. With its emerald green hills, South island is a paradise.
Green Hill: a coastal paradise, the first stage of the previous game.
Ocean Wind: a coastal area with rocky islands that likely had pine trees.
Woods: a deep forest, also called Secret Jungle.
Sand Shower: a new area from when the island rose out of the water, this dry desert has ancient ruins, cacti, and sinking sand.
Metropolis: the ancient warp point pyramid rose from the ocean and was restored with steampunk technology by Dr. Ivo "Eggman" Robotnik. Legends say it was an ancient time machine.